A relay network system includes a plurality of relay nodes connected to each other to constitute a relay network and one or more blockchain peer nodes connected to the relay nodes. Each relay node receives at least one of a connection packet including connection request information and a block packet including block information at the user level, transmits the block packet to a connected blockchain peer node and another relay node, and updates a connection information table so that information on the connection to the blockchain peer node and relay node connected to transmit or receive the block packet corresponds to the connection packet.